Both forehands are good, they probably wouldn't complement either of their games. However Federer's forehand would probably be a little more effective for Nadal's game than Nadal's forehand for Federer's game.

changing Nadal to Fed's FH would make him much more dangerous. He could outlast you or launch an attack with that missile launcher that Federer has. Ironically, if Nadal had Fed's FH, it would be a better matchup for Fed.

Both forehands are good, they probably wouldn't complement either of their games. However Federer's forehand would probably be a little more effective for Nadal's game than Nadal's forehand for Federer's game.

Whatever the outcome, they would have the ugliest tennis form known to man. Nadal's forehand on the Fed body, with a 1hbh would be just awkward. The same goes for Fed's Fh on Nadal body. And they probably would have as many fans, lol.